Which diuretic is classified as a loop diuretic?

Furosemide is classified as a loop diuretic because it acts on the loop of Henle in the nephron of the kidney. Loop diuretics like furosemide inhibit the sodium-potassium-chloride co-transporter in this segment, leading to increased excretion of sodium, chloride, and water. This makes furosemide highly effective for conditions characterized by fluid overload, such as heart failure, renal impairment, and hypertension.

In comparison, hydrochlorothiazide is a thiazide diuretic, which works primarily in the distal convoluted tubule. Spironolactone is a potassium-sparing diuretic that acts on the collecting ducts and is an aldosterone antagonist. Aldactone is an alternative name for spironolactone. These other options do not exert their effects on the loop of Henle, which is the hallmark of loop diuretics. Therefore, furosemide stands out as the correct choice for this classification.